Dry-kiln for lumber, &amp;c.



J. M. LEAVER.

DRY KlLN FOR LUMBER, 8m.

APPLICATION FILED APR. 4, 1914.

Patented Apr. 13, 1915.

5 SHEETSSHEET 1.

WITNESSESQ Leave/ ATTORN EY THE NORRIS PETERS CO,v F'HOTVLITHQ. WASHINGTON D C.

NVENTOR J. M. LEAVER.

DRY KILN FOR LUMBER, 8L0.

APPLICATION FILED APR. 4, I914.

L15 U Patented Apr.13, 1915.

5 SHEETS-SHEET 2.

6% E g 5 I i i i E i I 1 I I I [M INVENTOR 'Q I m BY 1 I ATTORNEY THE NORRIS PETERS 60.. PHOTO-LITHO.. WASHINGTON, D. C.

J. M. LEAVER. DRY KILN FOR LUMBER, &c.

APPLICATION FILED APR.4, 1914.

Patented Apia-13, 1915.

6 BHBETSSHEET 3.

ATTORNEY THE NORRIS PETERS c0, PHOTC-LITHQ. WASHINGTON. D. C.

J. M. LEAVER.

DRY KILN FOR LUMBER, an.

APPLICAHON FILED APR.4,1914.

Patented Apr. 13, 1915.

5 SHEETSSHBET 4.

3 JMM- ATTORN EY THE NORRIS PETERS CO., FHOTO-LITHCL. WASHINGTON. D. 1?v

J. M. LEAVER.

DRY KILN FOR LUMBER, 61c.

APPLICATION r1150 APR.4, 1914.

6 SHEETS-SHEET 5.

Patented Apr. 13, 1915.

INVENTOR WITNESSES ATTORN l -IY THE NORRIS PETERS 60.. PHoTc-LITHQ. WASHINGTON. D. C,

JAMES M. LEAVER, OF LONG BEACH, CALIFORNIA.

DRY-KILN FDR LUMBER, 85o.

niaaeoa.

Specification of Letters Patent.

Patented Apr. 13, 1915.

Application filed. April 4, 1914. Serial No. 829,594.

To all w/zom it may concern Be it known that 1, JAMES M. LEAVER, a citizen of the United States, residing at Long Beach, in the county of Los Angeles and State of California, have invented a new and useful Dry-Kiln for Lumber, &c., of.

which the following is a specification.

The invention relates to improvements in kilns for drying lumber and other material.

The object of the present invention is to improve the construction of dry kilns, more especially that shown and described in an application filed by me on or about May 24, 1912, Serial No. 699,578, and to eliminate wood and similar material in the construction of such kilns and enable hollow tile and cement to be utilized in such construction, and to provide a simple, strong and practical kiln of comparatively inexpensive construction, equipped with a relatively large recir culating duct or passage extending the entire length of the kiln room or drying chamber and containing heating means adapted to insure the greatest possible velocity of internal circulation and cause recirculated hot moist air to commingle with the currents of the outside air entering the drying chamber or kiln room at the top thereof at one side of the same, whereby a mixture of two currents is effected during the passage of the same across the drying chamber through the space between the roof or ceiling and the load of lumber or other material to be dried before reaching the latter.

A further object of the invention is to provide a dry kiln of this character adapted to maintain great internal circulation without depending for the same upon the escape of hot moist air to a chimney or stack, and at the same time to enable such draft to be utilized for carrying away and effecting the desired reduction of the moisture, and to main tain the proper amount of moisture within the kiln, and to control admission of the cold or outside air to the drying chamber or kiln room and permit a gradual reduction of moisture and an increase of heat as the drying process progresses.

It is also an object of the invention to provide a dry kiln having means for maintain ing perfect control of the temperature and moisture at all times and in which the internal circulation may be maintainedwiththe temperature and moisture desired, thereby producing ideal conditions for the proper drying of all kinds of lumber and various other material.

Another object of the invention is to provide a dry kiln having its ducts or passages arranged so as to produce an internal circulation transversely of the drying chamber or kiln room and in which the intensity of the circulation will not be interrupted or interfered with by the control of the draft to the chimney or stack and which will be assisted and accelerated by such draft, and which will also admit of a graduation in temperature from one end of the kiln room to the other for progressive drying, or the maintaining of a uniform temperature from one end of the drying chamber or kiln room to the other to dry uniformly all the lumber or other material so that the entire contents of the kiln room or drying chamber may be dis charged at one time when the drying has proceeded as far as desired.

With these and other objects in view, the invention consists in the construction and novel combination of parts hereinafter fully described, illustrated in the accompanying drawings, and pointed out in the claims hereto appended; it being understood that various changes in the form, proportion, size and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings :Figure l is a side elevation of a hollow tile and cement dry kiln, constructed in accordance with this invention. Fig. 2 is a longitudinal sectional view of the same. Fig. 3 is a horizontal sectional view of one side of the kiln, illustrating the construction and arrangement of the cold air inlet box. F ig. 4k is an elevation on a larger scale of the lower end of the dry kiln. Fig. 5 is a longitudinal sectional view on the line 5--5 of Fig. 4. Fig. 6 is a transverse sectional view on the line 66 of Fig. 5. Fig. 7 is a horizontal sectional view on the line 7-7 of Fig. 6. Fig. 8 is a detail sectional view, illustrating the arrangement of the gutter. Fig. 9 is a detail view of one of the moist air outlets.

Like numerals of reference designate corresponding parts in all the figures of the drawings.

In the accompanying drawings in which is illustrated the preferred embodiment of the invention, the dry kiln, which may consist either of a single drying chamber or kiln room 1, or a series of the same, comprises in its construction side walls 2 and 3, upper and lower end walls 4 and 5, a floor 6, and a longitudinally inclined roof 7. The walls are constructed of hollow tiles and the side walls are arranged upon concrete foundations 8, preferably supported by piles 9 having their upper ends embedded in the cement of the foundation, but the latter may be arranged upon any other suitable solid support. The concrete floor 6, which has a slant from the upper end wall 4 to the lower end wall 5 of the kiln, is preferably arranged upon a bed 10 of gravel or other suitable material. The foundations 8 are stepped at intervals, as shown atll to. provide a series of horizontal supporting surfaces at different. elevations to enablethe hollow tiles to be supported in a plumb position by the foundations at opposite sides of the inclined floor 6. The side walls are surmounted by concrete caps 12 and the upper and lower end walls by concrete caps 13 and 14, the said concrete caps being preferably reinforced at the base by woven wire 15, arranged upon the uppermost tiles of the walls of the kiln, but any other suitable reinforcing material may, of course, be employed.. The side caps 12 are stepped at their lower faces at 16 and have longitudinally inclined upper faces 17, corresponding .to the slant of the roof, which is supported at intervals by transverse concrete beams 18. The beams are preferably reinforced bycorrugated bars 19, and the spaces or intervals between the ends of'the beams are filled by hollow tiles to complete the side walls. I o I The upperand lower end walls 4 and5 are provided at their upper portions with horizontal channel beams 20 and 21, having their side walls or flanges extended upwardly and partially embracing a series of tiles, which support the concrete end caps 13 and 14. The endcap 14 at the lower end wall of the kiln is located at the lower end of the inclined roof and is provided in its upper face with a longitudinal groove 22 forming a gutter and having an extended outer wall 23, as clearly illustrated in Fig. 5 of the drawings. The groove or gutter is inclined and slants downwardly from the center to each end of the end cap 14, and the latter is oppositely tapered from its center to its ends and has a horizontal lower face, the

upper faces or edges of the inner and outer walls of the groove or gutter 22 being inclined laterally with respect to the kiln. The inner wall of the groove or gutter is arranged in flush relation with the concrete roof and the water, which runs off the roof into the gutter, drains from thecenter to the ends thereof. The roof extends over the upper concrete end cap and over the concrete side caps, and it is provided at its upper end and sides with projecting ribs or portions 24 having inclined side faces and adapted to prevent the water from flowing over the upper ends and sides of the roof, and the said ribs confine the water and cause the same to flow downwardly along the roof to the gutter at the lower end thereof.

The side wall 2 is provided at intervals with vertical cold air ducts or passages 25, formed by the hollow tiles, each vertical set or series of duct-forming tiles providing a pair of ducts or passages having upper and lower openings 26 and 27 located at the inner walls of the ducts or passages, as clearly illustrated in- Fig. 6 of the drawings. The lower openings 27 communicate with a bottom cold air intake box 28, arranged upon the concrete floor of the kiln contiguous to the side wall 2 and extending the entire length of the kiln. The cold air intake box, which may be constructed of any suitable material, is composed of inner and outer side walls 29 and 30 and a top wall 31, the concrete floor 6 constituting the bottom wall of the box. The cold air intake box is provided at its outer. side wall 30 with lateral openings 32, registering with the lower openings 27 of the cold air ducts or passages and adapted to permit cold air from the outside of the kiln to pass upwardly through the ducts or passages 25 and enter the drying chamber or kiln room at the top thereof through the openings 26. The cold air intake box has a central transverse partition 33 dividing the said box into two separate portions or sections, which are closed at their inner ends by the said partition 33. The upper and lower end walls of the kiln are provided at the ends of the cold air intake box with substantially rectangular metallic frames or casings 34, preferably consisting of castings and mounted in the end walls of the kiln and constituting reduced mouths or entrance openings for the cold air intake box. The frames or casings 34, which are of a width corresponding to the thickness of the adjacent portions of the end walls, are equipped with adjustable doors or dampers 35, hinged to the tops of the frames or casings and provided at their lower free edges with chains 36, adjustably engaging rocks 37, mounted upon the exterior of the end walls above the doors or dampers 30 and adapted to support the same in an open position. Any other suitable means may be employed for adjusting the dampers or doors 35, which are exteriorly operable to 1control the admission of cold air into the riln.

The kiln is provided at the inner face of the side wall 2 with a recirculating duct or passage 38 formed by a partition 39, constructed of galvanized sheet metal or other suitable material and spaced from the side wall 2 and extending the entire length of the kiln and from a point slightly above the intake box to a point adjacent to the horizontal plane of the upper openings 26. The partition 39 may be secured at its lower edge to the radiator stands, as clearly shown in Fig. 6 of the drawings, but it may terminate short of the said stands to increase the size of the lower inlet to the recirculating duct or passage 38. The lower inlet may be varied to any extent so long as the radiator is not entirely exposed, and a portion of it is located within the recirculating duct. The partition 39 is supported near the center and upper edges by brackets 41, which may be of any desired number, and which may be located at any suitable points to provide the necessary support for the partition 39. The brackets 41, which may be constructed of strap iron or other suitable material, consists of upper horizontal portions and lower inclined braces, and they are suitably -secured to the wall of the kiln, preferably by extending the horizontal portions through the said wall and terminating the inclined portion at the inner face of the wall. The horizontal inclined portions of the brackets are provided with depending vertical extensions, which fit against the outer and inner faces of the side wall, but the brackets may be mounted on the said side wall in any other suitable manner. The lower portion 7 42 of the partition 39 is arranged at a slight inclination to form an upwardly tapered intervening space between the lower portion of the partition and the side wall 2 of the kiln for the reception of heating devices preferably in the form of steam radiators 43, connected with longitudinal feed and return pipes 44 and 45 and adapted to heat the air in the lower portion of the recirculating duct or passage 38 and cause the same to rapidly ascend and reenter the drying chamber or kiln room at the top thereof adjacent to the openings 26 where the cold air from the outside enters the kiln room, thereby causing a mixing and commingling of the cold outside air with the hot moist air as the same passes over the lumber 46 or other material to be dried. The feed and return pipes enter the kiln at the lower end wall thereof and pass through a metallic box or casing 47 preferably consisting of a casting and designed to be filled with concrete or other suitable material, which closes the space around the feed and return pipes. The steam pipes are designed to be provided at suitable points with controlling valves 48 for enabling the degree of heat to be regulated to produce the desired conditions. The partition 39 is provided at its upper edge with an inclined portion or flange 49, which extends upwardly and inwardly and the said stands are provided with projecting bracket arms 50, which extend inwardly beneath the lower edges of the partition 39, an angle bar or strip 51 being preferably employed for connecting the said partition 39 to the bracket arms 50. The intermingling currents from the recirculating duct or passage and the cold air ducts or passages pass over and through the lumber 46 or other material traversing the drying chamber or kiln room transversely and passing downwardly at the opposite side of the drying chamber or kiln room from that at which the recirculating duct is located, portions of the hot moist air escaping through outlet ducts or passages 52 of the side wall '3. The outlet ducts or passages 52, which are arranged at intervals, are formed by vertical tiers or series of hollow tiles, which like the hollow tiles of the cold air ducts or passages form a pair of outlet ducts or passages 52 at each series of hollow tiles. The outlet ducts or passages are provided at their lower ends and at points intermediate of their ends with moist outlet openings 53 and 54, and they have extended upper ends 55 projecting above the roof 7 and constituting chimneys. The intermediate and lower moist air outlet openings are controlled by slides 56, mounted in grooves or ways 57 of the frames or castings 58 and adapted to be adjusted to close the outlet openings or to partially or fully open the same. The slides, which are adjusted from the interior of the kiln, permit either the lower or intermediate moist air outlet openings to be used to produce the desired con ditions of drying, or both the intermediate and lower outlet openings may be operated at the same time to the desired extent. The suction through the outlet ducts or passages with their chimney extensions positively draw off portions of the hot moist air and enable the escape of the same to be regulated and controlled.

The side wall 3 constitutes an intermediate wall separating two adjacent drying chambers or kiln rooms 1 when the same are arranged in a series, as illustrated in the accompanying drawings, and the said side wall 3 is provided at intervals or spaces between the outlet ducts or passages with the cold air inlet ducts or passages 25, communicating at their lower ends with the cold air intake box 28 of the next adjacent kiln room or drying chamber 1, which is provided with a recirculating duct orpassage 38 and radiators 43. The action or operation of the cold air 5 ducts is controlled by exterior. dampers, and it is unnecessary to provide interior dampers at the points 'where the cold outside air mixes with the hot moist air of the recirculating duct. The walls of the cold air ducts or passages are more or less heated by the close proximity of the radiators, and the outside air in passing upwardthrough the saidcold-air ducts or passages has its temperature raised so that when the outside or cold air meets the reheated moist air, it is higher in temperature than the outside air, this .varying with the volumeadmitted and the temperature of the cold air ducts, By arranging the vertical heating or recirculating duct and the cold air' ducts at one wall of the drying chamber and the outlet ducts at the opposite wall the outlet ducts when open cause the currentsto pass across the drying chamber, the moist air outlet 5 openings of the outlet ducts assisting the down draft. The up draft through the re circulating duct and the downdraft within the kiln room or drying chamber produces a very strong internal circulation. The reheated and recirculatedhot moist air strikes the currents of outside air and mixes with the same as the currents pass across the top of the drying chamber or kiln roomrat the space between the roof or ceiling and the lumber or other material to be dried. The tendency of the mixed currents is to descend adjacent tothe side-wall 3, and they pass through" the courses of'lumber while traveling toward the outlet ducts or pas- 40 sages and the moisture may be permitted to escape as slowly or as rapidly as desired and the material may be maintained at a uniform temperature throughout the kiln or the temperature may be graduated for progressive drying.

The'lumber is piled upon a car 59, arranged upon a track, the rails 60 being supported by vertical-posts 61 suitably braced and mounted upon vertical piers 62 of concrete or other suitable material. The piers 62, which are preferably provided with enlarged concrete bases 63, are arranged plumb while the tracks have the same slant or inclination as the floor of the kiln. The

end walls of the kiln are provided with door openings and are equipped with sliding doors 64, but doors of any suitable construe tion may, of course, be employed. The kiln is provided adjacent to the end walls with concrete blocks 65 for supporting the kiln platform post (not shown);

What is claimed is 1. A dry kiln including a drying chamber, a plurality of cold air ducts located at 65, one vside of the drying chamber and extending from the bottom to the top thereof and communicating at their lower ends with the outside atmosphere and at their upper ends with the drying chamber, and a continuous reheating and recirculating duct located at such side of the drying chamber and communicating at the top and bottom with the same and having its top portion arranged adjacent to the upper ends of the cold air ducts to cause acommingling of the hot moist air with. the cold air as the latter enters the drying chamber, and heating means arranged to produce a positive upward draft through the reheating and recirculating duct.

2. A dry kiln including a drying chamber provided within one of its walls with a cold air duct or passage extending from the bottom portion to the top portion of the drying chamber and communicating at its lower end with the outside atmosphere and at the upper end with the drying chamber,

.a reheating and recirculating duct or passage -located at the inner face of such wall and communicating at the top and bottom of the drying chamber and having its top located adjacent to the upper end of the cold air duct or passage to cause a commingling of hot moist air with the cold air as the latter enters the drying chamber, and 5 heating means arranged to produce a positive upward draft through the reheating and recirculating duct.

3. A dry kiln including a drying chamber, a cold air intake box arranged within the drying chamber at the bottom thereof and communicating with the outside atmosphere, a cold air duct or passage located within one of the side walls of the kiln and communicating at its lower end with the cold air intake box and at its upper end with the drying chamber, a partition located above and in spaced relation with the cold air intake box and spaced from the adjacent wall of the kiln to form a reheating and recirculating duct or passage having its top arranged adjacent to the upper end of the cold air duct or passage to cause a commingling of hot moist air with the cold air as the latter enters the drying chamber, and heating 115 means arranged to produce a positive upward draft through the reheating and recirculating duct.

4:. A dry kiln including a drying chamber provided within one of its side walls 1 0 with cold air ducts or passages arranged at intervals and communicating at its upper end with the drying chamber, a cold air intake box arranged at the bottom of the drying chamber and extending along the said 125 wall and communicating with the lower ends of the cold air ducts or passages and with the outside atmosphere, a partition spaced from and extending along the said Wall and forming a reheating and recirculating duct 130 or passage communicating at the top and bottom with the drying chamber and having its top arranged adjacent to the upper ends of the cold air ducts or passages, and heating means supported by the cold air intake box and extending into the reheating and recirculating duct or passage to produce a positive upward draft through the same.

5. A dry kiln including a drying chamber, cold air ducts or passages arranged within the side wall of the said chamber and communicating at their upper ends with the same, a cold air intake box extending along the bottom of the drying chamber and communicating with the outside atmosphere and connected with the lower ends of the said cold air ducts or passages, a partition spaced from the said side wall and forming a reheating and recirculating duct or passage communicating at the top and bottom with the drying chamber, a radiator located with in the lower portion of the reheating and recirculating duct or passage, and radiator stands mounted on the cold air intake box and supporting the radiator and connected with the lower edge of the said partition.

6. A dry kiln including a drying cham ber provided at the side wall with a plurality of cold air ducts or passages communicating at their upper ends with the drying chamber and at their lower ends with the outside atmosphere, a partition spaced from such wall of the drying chamber and forming a reheating and recirculating duct or passage having its top arranged adjacent to the upper ends of the cold air ducts to cause a commingling of moist air and the cold air as the latter enters the drying chamber, a radiator arranged within the reheating and recirculating duct or passage and supporting the lower edge of the partition, and brackets mounted on the said side wall and connected with the said partition.

7. A dry kiln including a drying chamber, cold air ducts or passages arranged at the side of the drying chamber and communicating at their upper ends with the same and at their lower ends with the outside atmosphere, a partition spaced from such wall of the drying chamber and forming a reheating and recirculating duct or passage having its top arranged adjacent to the upper ends of the cold air ducts or passages to cause a mixing of hot moist air and cold air as the latter enters the drying chamber, said partition having an inclined lower portion and provided at the top with an inclined flange forming a flaring outlet.

8. A dry kiln including a drying chamber, a cold air intake box arranged within and extending throughout the entire length of the drying chamber and communicating at its outer ends with the drying chamber and provided at an intermediate point with a partition, cold air ducts located at intervals at the side of the drying chamber and communicating at their lower ends with the said cold air intake box and at their upper ends with the drying chamber, a partition spaced from the said side of the drying chamber and forming a continuous reheating and recirculating duct or passage communicating at the top and bottom with the drying chamber and having its top arranged adjacent to the upper ends of the cold air ducts or passages to cause a commingling of hot moist air and the outside air as the latter enters the drying chamber, and heating means arranged within the reheating and recirculating duct or passage to produce a positive upward draft through the same.

9. A dry kiln including a drying chamber, a cold air intake box arranged at the bottom of the drying chamber and communicating with the outside atmosphere, cold air ducts located at the side of the drying chamber and connected at their lower ends with the cold air intake box and at their upper ends with the drying chamber, a reheating and recirculating duct or passage communicating at the top and bottom with the drying chamber and having its top portion arranged adjacent to the upper ends of the cold air ducts or passages, heating means located within the reheating and recirculating duct or passage, and a damper for controlling the passage of cold air through the said intake box.

10. A dry kiln including a drying chamber, cold air duets located at one side of the drying chamber and connected at their lower ends with the outside atmosphere and at their upper ends with the drying chamber, and a continuous reheating and recirculating duct or passage arranged at such side of the drying chamber and having its top portion located adjacent to the upper ends of the cold air ducts or passages to cause a mixing of hot moist air with the cold air as the latter enters the drying chamber, heating means within the reheating and recirculating duct or passage, and outlet ducts or passages located at the opposite wall of the drying chamber and constituting chimneys or stacks and provided with moist air outlets communicating with the drying chamber.

11. A dry kiln including a drying chamber, cold air ducts located at one side of the drying chamber and connected at their lower ends with the outside atmosphere and at their upper ends with the drying chamber, and a continuous reheating and recirculating duct or passage arranged at such side of the drying chamber and having its top portion located adjacent to the upper ends of the cold air ducts or passages to cause a mixing of hot moist air with the cold air as the latter enters the drying chamber, heating means within the reheating and recirculating duct or passage, and a plurality of outlet ducts or passages located at the opposite wall of the drying chamber and provided with moist air outlets communicating with the. said chamber.

- 12. A dry kiln including a drying chamber, cold air ducts located at one side of the drying chamber and connected at their lower ends with the outside atmosphere and at their-upper ends with the drying chamber, and a continuous reheating and recirculating duct or passage arranged at such side of the drying chamber and having its top portion located adjacent to the upper ends of the cold air ducts orpassages to cause a mixing of hot moist air with the cold air as the latter enters the drying chamber, heating means within the reheating and recirculating ductorpassage, and a plurality of outlet ducts or passages located at the opposite wall .of the drying chamber and provided with moist air outlets communicating with the said chamber, ,said outlet ducts being provided at the top with extensions projecting above the kiln and forming chimneys.

13. A dry kiln including a drying chamber, ,a plurality of cold airducts located at one side of the drying chamber and communicating at their upper ends with the same, a continuous reheating and recirculating duct orpassage arranged at such side ofthe drying chamber in position to cause hot moist air to mix with the cold air as the latter entersthe drying chamber, and a plurality of outlet ducts or passages located at the opposite wallof the drying chamber iLIlCl. provided with controlled moist air outets. 7 l.

14. A dry kiln including a drying chamber, a plurality of coldair ducts located at one side of the drying chamber and communicating at their upper ends with the same, a continuous reheating and recirculating duct or passage arranged at such side of the drying chamber in position to cause hot moist air to mix with the cold air as the latter enters the drying chamber, and a plurality of outlet ducts or passages located at-the opposite wall of the drying chamber and provided with moist air outlets located at different elevations.

- 15. A dry kiln including a drying chamher, a plurality of cold air ducts located at one side-of the drying chamber and communicating at their upper. ends with the same, a continuous reheating and recirculating duct or passage arranged at such side of the drying chamberin position to cause hot moist airto mix with the cold air as the latter enters the drying chamber, and outlet ducts or passages located at the opposite side-of the drying chamber and provided at their lower ends and at points interme diate of their ends with moist air outlets.

16. Adry kiln including a drying chamber, cold air ducts or passages located at one side of the drying chamber and communicating at their lower ends with the outside atmosphere and at their upper ends with the said chamber, a continuous reheating and recirculating duct or passage arranged at the said side of the drying chamber in position to cause a mixing of hot moist air with the cold air as the latter enters the drying chamber, outlet ducts located at the opposite side of the drying chamber and provided with moist air outlets communicating with the said chamber, means for controlling the passage of air through the said moist air outlets, and separate means for controlling the passage of cold air to the said cold air ducts or passages.

17. A dry kiln including a drying chamber, means for introducing cold air into the same, means for reheating and recirculating the hot moist air and for mixing the same with the cold air as the latter enters the drying chamber, and an outlet duct or passage provided with moist air outlets located at different elevations, and means for controlling the passage of air through the said outlets.

18. A dry kiln including a drying chamber provided with a vertical outlet duct or passage extending upwardly from the lower portion of the drying chamber and communicating at its upper end with the outside atmosphere, said outlet duct or passage having moist air outlets arranged at different elevations.

19. A. dry kiln including a drying chamber, a cold air intake box extending along the dryin chamber at the bottom thereof, an inlet not or passage located at one of the side walls of the drying chamber and communicating at its lower end with the cold air intake box and at its upper end with the drying chamber, an outlet duct or passage arranged at the opposite wall of the drying chamber and communicating with the latter and with the outside air at the top of the kiln, a recirculating duct or passage communicating at the top and bottom with the drying chamber and having its upper end arranged adjacent to the upper end of the cold air duct or passage to cause a commingling of hot moist air and cold air as the latter enters the drying chamber, and heating means located within the recirculating duct or passage for producing a positive upward draft through the same.

20. A dry kiln including a drying chamber, a cold air intake box extending along the drying chamber at the bottom thereof, a cold air duct or passage located at one side of the drying chamber and communicating at its lower end with the cold air intake box and at its upper end with the drying chamber, a recirculating duct or passage located at such side of the drying chamber and communicating at the top and bottom with the same and having its top arranged adjacent to the upper end of the cold air duct to cause a commingling of the cold air with the hot moist air as the former enters the drying chamber, and heating means located within the recirculating duct or passage to produce a positive upward draft through the same.

21. A dry kiln including a drying chamber having hollow tile walls forming vertical cold air and outlet ducts or passages arranged in pairs, the cold air ducts or passages having upper and lower openings communicating, respectively, with the drying chamber and with the outside atmosphere and the outlet ducts or passages having lower openings communicating with the drying chamber.

22. A dry kiln including a drying chamber having side and end Walls a cold air intake box extending along the drying chamber from one end wall to the other, frames or casings mounted in the end walls and forming reduced mouths or inlets for the cold air intake box, dampers carried by the said frames, and cold air ducts or passages connecting the intake box with the interior of the drying chamber.

23. A dry kiln including a drying cham ber provided at one side wall with a recirculating and reheating duct, heating means located within the duct for causing an upward draft through the same, and means for introducing cold air from the outside atmosphere into the kiln at the top of the recirculating and reheating duct to cause a mixing of the cold air with the hot moist air.

24. A dry kiln including a drying chamber provided at one of its side walls with a continuous reheating and recirculating duct, heating means for causing an upward draft through the reheating and recirculating duct, and means for introducing cold air into the kiln at a plurality of points along the top of the reheating and recirculating duct.

In testimony that I claim the foregoing Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

